Fossil fuels are normally stored in a reservoir deep in the earth. the carbon in fossil fuels, including coal and oil, are essentially locked out of the natural carbon cycle due to their location deep in the earth. humans have found a way to access and utilize this carbon. identify a risk for accessing this carbon. scientists conclude that excess carbon will reduce the need for other nutrient cycles. scientists feel that the extra carbon will assist in plant growth. scientists are not sure if the atmosphere can handle all of the excess carbon.